PRESSURE BOOSTER UNITS

use of the same.
N.B. By connecting a float or minimum pressure pressure switch to
the control panel (whether for withdrawal from the primary
collection reservoir or from the hydraulic circuit), the most frequent
cause of electric pump breakdown is prevented: the lack of water at
suction.

FUNCTIONING PRINCIPLE
OF THE PRESSURE BOOSTING UNIT GPE

The GPE unit is designed to function with a pump governed by a
frequency converter “INVERTER” inserted into the electric control
panel and the others with direct intervention.
This unit, thus constructed, allows to maintain constant pressure in
the water network.
On variation of the network pressure, the INVERTER governed pump
varies its own rotation speed, stating the pressure of the set value.
Whenever the water withdrawal should exceed the pump flow rate,
the second pump intervenes directly and, in the meantime, that
governed by the INVERTER goes into regulation mode in order to
keep the water pressure at the set value. This takes place for all of
the pumps making up the unit.
When the withdrawal has been closed, the pump governed by the
INVERTER reaches the minimum rotation value and, after a few
minutes, stops allowing to obtain a large energy saving.
It is possible to have various versions of the GPE units:
• With an individual INVERTER, which governs just one pump, but
different from the previous start-up (Standard EFC Version).
• With multi-inverter, where every pump is controlled by an inverter
(MFC versions and HERTZ TWIN versions).
Contolling a unit via SP EFC control panels
The SP EFC for controlling units with several pumps envision
powering the pump n°1 via inverter in order to modulate
performance of the system depending on the reference signal,
while the other electric pumps are made to work at maximum
nominal speed (about 2900 min-1) wi th inser t ion and
disconnection in sequence on variation of the request.
This implies the presence of two distinct primary electric
circuits:
1st- pump start-up via inverter, 2nd- start-up (direct of deltatriangle)
of the other pumps, by contactors.
The system is governed by the “SYSTEM CONTROLLER” control
unit on the basis of the reference signal, which derives from a
pressure transmitter, flow rate measuring device or other
unified control signal (4÷20 mA passive).
• In the case of water distribution with constant start pressure
(Fig.1) , the cont rol uni t i s connected to the pres sure
transmitter positioned in the discharge manifold of the unit
that will send a proportional signal to the network pressure.
The lower ing of the network pressure, fol lowing water
withdrawal, causes a reduction of the pressure transmitter
signal, which, via the control unit, will control start-up, via
inverter, of the first pump regulating its speed in a way to reestablish
the reference/work pressure. If the flow rate of the
pump is lower than that requested, the network pressure will
tend to decrease and the system will react by increasing the
pump rotation speed. Once the maximum speed of pump n°1

DEFINITION AND USE
OF THE PRESSURE BOOSTER UNITS

If the public water distribution system is inexistent or insufficient for
correct functioning of the utilities, it is necessary to install a
pressure boosting unit in order to guarantee an acceptable pressure
and amount of water also in the most unfavourable points of use.
The pressure boosting unit is applied every time the pressure must
be increases or where the mains water must be pressurised.
The GPs, EBARA pressure boosting units, are small automatic
systems with 2 or more pumps in parallel, studied and realised
s imply and rel iably to sat i s fy the mos t recur rent pres sure
maintenance requests in the water supply of condominiums, hotels,
centres, offices, schools, auxiliary services in the industrial and
agricultural ambit. They are distinguished for the construction
strength, compactness, high efficiency and silence.The GP units are set-up for the membrane autoclaves or air pocket
connection.
Start-up of the individual pumps is caused by the activation of
pressure switches, appropriately calibrated via an electric control
panel. In the units controlled with electric control panel with
INVERTER, as well as pressure switches, one of the pumps is started
via the calibration of a pressure transducer.

If water is requested, this is initially withdrawn from the autoclave
reservoir, whenever the system is provided.
This consumption of water or, however, the escape of water from
the system, with pumps off, determines the lowering of the
pressure to a value such to trip the closure of the pressure switch
contact with higher calibration, which determines the ignition of
the first electric pump.
If the outlet discharge exceeds the flow rate of a pump, the
pressure continues to drop until it causes the closure of the contact
of the second pressure switch and the start-up of the second pump.
This takes place for all of the electric pumps that make up the unit.
The end of the distribution of the reduction of the outlet discharge
leads to the pressure in the system rising, with opening of the
pressure switch contacts and staggered pumps stops. The inversion
of the ignition order of the motors reduces the number of hourly
start-ups of the individual pumps and consequently a homogenous